from abc import ABC, abstractmethod
import io

class StorageService(ABC):
    """统一的存储服务接口"""
    
    @abstractmethod
    def upload_file(self, path: str, file_obj: io.BytesIO, length: int):
        """上传文件"""
        pass
    
    @abstractmethod
    def download_file(self, path: str) -> bytes:
        """下载文件"""
        pass
    
    @abstractmethod
    def delete_file(self, path: str):
        """删除文件"""
        pass